I doubt if changing the oil
will help, but changing the filter might. A dirty filter can change the oil pressure, which might be enough to trip the oil pressure switch in some conditions.
Could also be low fuel - the genny fuel pick-up is well above the bottom of the rv's tank, typically around the 1/4 tank level. A tight turn could lead to fuel starvation.
If this is oneof the later model 55's, it will flash a diagnostic code on the start switch light if there is an actual fault, e.g. low oil. Your owner manual should give the fault light and code info under the operator controls section. If you don't have the manual, this one may apply to yours (there are several versions of the Guardian 55.